How faithful these little workmen are! Not for an instant do they leave their tasks. Verily, they are the sentinels forever at the portals. In our work, in our pleasures, they are ever active; in our sleep, they sleep not. Not for an instant do they cease watch. Is there a wound--be it a great rent or a tiny pin-prick, they are there in force to repair it, to wall up the breach and to make it whole--swarming to the rent as the Lowlanders to a break in the dike. Has a foreign substance penetrated the structure?--instantly they set about to expel it; but if this be impossible, they seal it in a capsule of impervious integument that it may do no harm, or, the least possible injury. [Sidenote: A seeming consciousness in the automatic action of the blood] If these little workmen are not conscious as we know consciousness, at least their work shows purposeful action, and when we see an obvious purpose definitely carried out by every available agency, we may be sure there is a consciousness back of it, whether it be like ours or not. But while these workmen are faithful--while they will stand to their tasks to the end, they are limited in their power, and will break ranks under long-continued hindrances. [Sidenote: The human body a power-plant] The human body is a power-plant, a combined engine and boiler, and there is a close analogy between this conscious, self-acting power-plant and the one that furnishes the power to generate electricity, or to turn the wheels of a factory. [Sidenote: Symptoms compared with electric light] When your electric lights grow dim, and the defect is not cured by renewing the lamps, then you are convinced that the trouble is elsewhere. If the lights in every part of the house are dim, you will know (if you are a skilful electrician--a good diagnostician) that the trouble is not in the electric nervous system of the house. It may be between your house and the electric station, but before taking the trouble to examine the line, ask those of your neighbors who are on a different line, whether their lights are dim. If they are, you may go to the electric station with reasonable certainty of finding the cause. [Sidenote: The stomach and the lungs of this leviathan]